Silencer



Aug. 10, 1943. R. B. 'BOURNE ETAL S ILENCER Filed Feb. '7, 1942 3 Sheets-Sheet l INVENTOR NR Si al @L w+ PY \\}f A %N J im HMM A m MUN )NN @L Aug. 10, 1943. R. B.. BOURNE ETAL S ILENGER 3 Sheets-Sheet 2 Filed Feb. 7, 1942 INVENTOR Aug- 10, 1943- R. B. BOURNE ETAL 2,326,613

SILENCER Filed Feb. 7, 1942 f5 SheebS-Sheet 3 jj. 10Q;

Patented Aug. 10, 1943 UNITED STATES PATENT CFFICE SILENCER Roland B. Bourne, West Hartford, and John P. Tyskewicz, Hartford, Conn., assignors to The Maxim Silencer Company, Hartford, Conn., a corporation of Connecticut Application February 7, 1942, Serial No. 429,862

7 Claims.

This invention relates to exhaust silencing devices and has particular reference to silencers operating upon the expansion chamber principle of the genera1 type shown in the Bourne Patent 2,264,195, November 25, 1941. One object of the invention is to improve upon devices of this general character so that the silencing effect of several chambers will be improved. A further object is to provide a device of this general character which will have unusually low back pressure. Additional objects will appear from the following description and claims.

The invention will now be described with reference to the accompanying drawings in which:

Fig. 1 is a longitudinal section through a silencer embodying the invention;

Fig. 2 is a section on line 2-2 of Fig. l.;

Fig. 3 is a section on line -3-3 of Fig. l;

Fig. d is a longitudinal section of a modified forin of silencer embodying the present invention;

Fig. 5 is a section on line 5 5 of Fig. 4;

Fig. 6 is a section on line 6-6 of Fig. 4;

Fig. 'l is a longitudinal section through a iur ther modification;

Fig. 8 is a section on line S- of Fig. 7;

Fig. 9 is a section on line -ii oi Fig. 7;

`Fig. 10 is a longitudinal section through a modified form;

Fig. ll is a section online Il-ii of Fig. 10;

Fig. 12 is a section 'on line I2--l2 of Fig. 10; and

Fig. i3 is a section on line I3-l3 of Fig. 10,

Referring to the form shown in Figs. 1 to 3, the cylindrical casing l having end headers II and I2 is provided with intermediate partitions i3 and I4 which divide the interior of the casing into chambers I5, IG, and Il. Extending through the header Il is a conduit I8 which preferably serves as the inlet conduit. This conduit passes through the partition I3 and in the form shown terminates close to the mid-point of the chamber I6. The conduit I8 is coupled to the chamber I5 through a slot I9 and a series of holes 20 which, assuming for example a conduit 2% inches in diameter, may be three holes each 1%; inch diameter` or the equivalent. The chamber I in this case will be about 2% inches long with a l0 inch diameter of the casing. The chamber I6 is made about 12 inches long and the conduit I8 communicates with it not only through its open end but also through the slot I9, which may be 1A; inch wide. The transverse header I3 is provided with the peripherally located holes I3', in this case three equi-spaced holes .35 inch in diameter. The purpose of these holes is to aord a small but direct path so that gas pulses in the chamber I5 may enter, in an attenuated form, the chamber I6 where they become mixed with the pulses entering chamber I6 through the slotted conduit I8. A path differential is thus established. Another purpose of the holes I3' is to prevent standing Waves in the chamber I6, the combination of the holes I3 Aand the chamber I5 conspiring to offer a cushioning effect on such waves in the chamber I6. The use of these holes results in additional attenuating effect for low frequencies of at least three decibels. The total back pressure is also slightly reduced. The size and number of holes Will vary, of course, with the dimensions of the silencer, but the dimensions given are substantially correct for the embodiment shown. The invention is not restricted to these proportions, but they may serve as an illustrative example. Extending through the header i2 is a conduit 2i which extends approximately one-half way into chamber il and communicates with it not only through its open end but also through a slot 22.

The chambers it and ii are connected by a plurality of tubes preferably provided with holes Zd as described i t'. e patent referred to. In addition to the conduits described and. which in general find Vtheir counterparts in the cited patent, the chamber: is connected to the chainn ber il' by a relatively small conduit Thus, if the conduits 23 are two in number and are 11/2 inches in diameter, as will be found suitable for the purpose, the conduit may be inch in diameter. This conduit also has a series of holes 26 preferably arranged at the half and quarter points and serving both to prevent shock excitation of the conduit and to bleed some of the gas and sound Waves into the chambers I6 and il, the remainder passing through the open end of the conduit 25.

In the form shown in Figs. 4 to 6 the casing 3G with headers 3| and 32 is divided by partitions 33 and 34 into chambers 35, 36, and 3l. Inlet and outlet conduits 38 and 39, and conduits 4U connecting the chambers 36 and 3l are arranged substantially as described in the rst form, with the exception that the conduits overlap a substantial amount, preferably terminating near the headers shown in Fig. 6. as it has been found that this type of construction will reduce the back pressure approximately ,3 I

The operation of the device described is to equalize gas pulses and reduce the intensity of sound waves by providing for them a plurality of paths'of dillerent lengths. By carrying a portion of the gas and sound waves directly to the chamber 31 through the pipes 25 and 4I the eiliciency of the silencer is greatly improved. At the same time it should be noted that the conduits 23 and 40 are located relatively close to the axial inlet and outlet conduits. It has been found that by so doing the back pressure is substantially reduced, apparently because the gases coming through pipe 38, for example, tend to pass to the outside of the chamber 36, ow rearwardly along the outer shell, and then again resume a forward direction in adjacency to the outside of the conduit 38. The action is something like the formation of a smoke ring, and the presence of the conduits 40 in the natural path of thegas causes less disturbance than if they were arranged further away from the central conduits. Apparently the bending of the pipe 4l toward the center has a similar effect. It will be understood that the dimensions given are illustrative only and represent one form of device which has been found particularly satisfactory. The invention may be employed in devices having other proportions.

Referring next to the form of device shown in Figs. 7, 8 and 9, the entire silencer is enclosed in a generally cylindrical casing having end headers 46 and 41. Intermediate partitions 48 and 49 divide the casing into chambers 58, 5|, and 52. Through the header 46 and the partition 48 extends a conduit 53 having an open end within the chamber 5I and having lateral escape openings, such as slot 54 and apertures 55 within chambers 5l] and 5I. The silencer may be run with either end as the inlet but it is preferable to use the conduit 53 as the inlet pipe. Considering first the portion of the gas that passes into the chamber 5i. it will be seen that a portion of this will go through the open end of the conduit and a portion through the slot 54. The gas within the chamber 5I passes through a plurality of conduits 56 which discharge both through open ends and through lateral slits 51 into chamber 52. Finally the gas is taken from chamber 52 through a conduit 58 having a lateral slot 59. The opposed conduits within the chambers may be overlapping as in chamber 5I or may terminate near the mid-point near chamber 52. In addition to these passages for the gas additional paths are provided. As previously mentioned, gas discharges from the conduit 53 into chamber both through slot 54 and holes 55. From the chamber 50 two courses are open. The first path is through a tube (Figs. 8 and 9) of relatively small cross section having an open end within the chamber 52 and being provided with lateral openings 6| in that chamber. This provides a path directly from the chamber 56 to the non-adjacent chamber 52. The partition 48 is also provided with a series of holes 62 leading directly into the chamber 5|. It has been found that with this type of construction Aan improved silencing action having very low back pressure will be obtained.

In the device of Figs. 10 to 13 the outer casing 65 is provided with end headers 66 and 61 and with a plurality of partitions 68, 69, and 10. Chambers 1|I 12, 13, and 14 are thus formed.

end and through a lateral opening 19 into thechamber 14 from whence it is exhausted through a slotted conduit 80. In addition to these gas paths the chamber 1I is connected to chamber 12 through holes 8| and to chambers 13 and 14 through a conduit 82 having an open end within chamber 14 and a series of lateral openings 83 into chambers 13 and 14. Chamber 13 is also provided with one or more conduits 84 leading into chamber 14 and preferably provided with lateral escape openings 85. In addition the partition 10 may be provided with a series of small holes 86 leading directly into the chamber 14. The purpose of these holes is as set forth in connection with the device of Fig. 1. In the various cases where discrete holes are used in conduits like 49 they are preferably placed at the half, quarter and eighth points in order to prevent shock excitation of the conduit as is described in the Bourne Patent 2,264,195. The chamber 13 may also be connected to pipe 82 through certain of the holes 83 and to conduits 18 through holes 81.

What we claim is:

1. A silencer comprising a substantially cylindrical casing divided transversely by a plurality of partitions into a series of chambers, an inlet conduit extending through the rst chamber and having an open end within the'second chamber and one or more openings into the first chamber, one or more conduits each provided with open ends in both second and third chambers and with one or more lateral escape openings, an exhaust conduit provided with one or more .lateral escape openings and with an open end in the third chamber, and a conduit extending from the first chamber through the second chamber and hav ing an open end within the third chamber.

2. A silencer comprising a substantially cylinf drical casing divided transversely by a plurality ofpartitions into a series of chambers, an inlet conduit extending through the rst chamber and having an open end within the second chamber and one or more openings into the first chamber, one or more conduits each provided. with open ends in both second and third chambers and with one or more lateral escape openings, an exhaust conduit provided with one or more lateral escape openings and withl an open end in the third chamber, a conduit extending from the rst chamber through the second chamber and having an open end within the third chamber, and holes through at least one of said partitions directly connecting the adjacent chambers.

3. A silencer comprising a substantially cylindrical casing divided transversely by a plurality of partitions into a series of chambers of lengths increasing progressively from the inlet to the outlet end, an inlet conduit extending through the i'lrst chamber and having an open end within the second chamber and one or more openings into the rst chamber, one or more conduits each provided with open ends in both second and third chambers and with one or morerlateral escape openings, an exhaust conduit provided with an open end in the third chamber and with one or more lateral escape openings, and a conduit extending from the first chamber through the second chamber and having an open end within the third chamber.

4. A silencer having at`least three longitudinally spaced chambers, a, first conduit extending into an intermediate chamber and coupled thereto both through its walls and through its open end, said conduit also being coupled to the end chamber through which it passes, a second conduit passing into the second end chamber and coupled thereto both through its walls and through its open end, one or more third conduits connecting the intermediate and second end chambers, and one or more fourth conduits connecting the iirst end chamber with the second end chamber.

5. A silencer having at least three longitudinally spaced chambers, a rst conduit extending into an intermediate chamber and coupled thereto both through its walls and through its open end, said conduit also being coupled to the end chamber through which it passes, a second conduit passing into the second end chamber and coupled thereto both through its walls and through its open end, one or more third conduits connecting the intermediate and second end chambers, and one or more fourth conduits connecting the rst end chamber at a point near the periphery thereof with the second end chamber at a point adjacent the second conduit.

6. A silencer having a generally cylindrical casingl three partitions dividing the casing into a first narrow chamber, a Asecond main chamber, a, third narrow chamber, and a fourth main chamber, a rst conduit extending into the casing,

through the first chamber, and terminating in an open end in the third chamber, a second conduit extending from the first chamber through the second chamber and terminating in an open end in the fourth chamber, a plurality of third conduits extending through the third chamber and having open ends within the second and fourth chambers, a fourth conduit; extending from the third chamber into the fourth chamber, and a fifth conduit extending through the end of the casing and terminating in an open end within the fourth chamber, there being lateral escape openings formed in the first conduitI within the first and second chambers, in the second conduit Within the third and fourth chambers, in the third conduit within the third and fourth chambers, and in the fourth and fifth conduits Within the fourth chamber.

7. A silencer comprising a first expansion chamber, an inlet conduit opening into the nrst expansion chamber, a second expansion chamber having an outlet conduit, and being connected to the first chamber by means of one or more conduits, a chamber surrounding said inlet conduit and acoustically coupled thereto through one or more apertures in the conduit, apertures in a wall separating said chamber from said first expansion chamber, and a conduit leading from said chamber directly to the interior of said second expansion chamber.

ROLAND B. BOURNE. JOHN P. TYSKEWICZ. 

